I don’t know much about electronics and from what I read on an instructable it was doable. I’m basically trying to stop using AA batteries for my wireless keyboard and wondered if I could just solder a usb cable for it to get power from a port.

Edit: A lot of comments on why I don’t just get another keyboard and how I’ll just have a wired keyboard... I never use the keyboard I just needed one quickly and for a short while.

  • \$\begingroup\$ Not directly, no. USB port puts out 5V. \$\endgroup\$ – DKNguyen May 15 at 19:57
  • \$\begingroup\$ Safe in what way? Safe for you, yes. Safe for the computer, yes, if you get it right, but no if you don't get it right, and you may end up with burnt USB ports. So depending on your skill level, consider buying a wired keyboard. In any case, they can't directly be connected, you need a 3V regulator, and whatever components it needs to operate. \$\endgroup\$ – Justme May 15 at 20:00
  • \$\begingroup\$ Then you end up with a wired keyboard. \$\endgroup\$ – Marla May 15 at 20:01
  • \$\begingroup\$ Why not get a USB keyboard, since you'd be using a USB cable anyway? \$\endgroup\$ – Peter Bennett May 15 at 20:02
  • \$\begingroup\$ I'd be interested to hear why you chose to omit which instructable you read. I can't really figure out your thought process here. \$\endgroup\$ – pipe May 15 at 20:02

No, but USB is 5.0V so if you add a suitable regulator you could power a 3V 50mA device.

Inexpensive modules are available from China. You could even use a ~$1.50 USB->RS232 module based on chips such as CP2102, which have a 3.3V regulator on-board and ignore the serial port.

If you directly apply 5V to a 3.3V device you run a high risk of permanently damaging it.

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